Prentiss is sending Lewis to the prison to do a cognitive evaluation on Reid, to try to reach his memories of his time in Mexico. Mr. Scratch has been spotted in Honduras. Three people are found dead hanging from stakes in the Arizona desert. All the victims were exceptional students, who had just returned to Arizona, and the team needs to find a link among them. JJ determines the unsub is savoring the victims' deaths. Reid is psychologically blocking whatever happened after he picked up the knife. The unsub, Ben Davis, has claimed another victim at a new crime scene. Davis has an abusive mother, Virginia. The latest victim was a college dropout. Alvez figures out the rocks represent positions on a sundial, and that he's near the end of his killing. Reid creates a false memory that he stabbed Rose Medina. Davis has kidnapped another victim, Marla Grace, who judged a science fair competition that Davis lost. All the victims were scholarship students. The water bottles were used to amplify the effects of shock collars the victims were wearing. Davis's mother suffers a stroke. He puts her feet in water, then tosses in an electric fan to kill her in front of Marla. The BAU arrives in time to save Marla, but Ben steps in water holding an electric heater. JJ cuts the power, then Alvez tackles and arrests him. Reid remembers a woman, not Scratch, spraying him with something, then handing him car keys.